A reação do lapachol à temperatura ambiente, com aminas alifáticas primárias forneceu novos adutos identificados como derivados do núcleo fenazina. Os produtos foram obtidos em rendimentos bons a razoáveis (52 a 88%), a temperatura ambiente e sem o uso de solvente, a partir da reação com alquilaminas funcionalizadas, como n-butilamina, etanolamina, 3-propanolamina, 2-metoxi-etilamina, 3-metoxi-propilamina e 2-feniletilamina.New adducts of lapachol with neat primary aliphatic amines were obtained in a solvent-free reaction in good to reasonable yields (52 to 88%), at room temperature. The new compounds containing a phenazine moiety were obtained from suitable functionalized aminoalkyl compounds, including ethanolamine, 3-propanolamine, 2-methoxy-ethylamine, 3-methoxy-propylamine, n-butylamine and 2-phenetylamine. Keywords: phenazines, lapachol, nitrogen adducts, quinones, 1,4-naphthoquinone IntroductionMolecules containing a quinone moiety as a structural component constitute an important class of compounds in organic chemistry. The conjugated 1,4-dicarbonyl or 1,2-dicarbonyl moiety is responsible for a characteristic reactivity behavior, yielding a somewhat particular chemistry repertoire for these compounds. These functional groups are also involved in numerous biological activities, mostly cytotoxic ones. The wide range of biological activities includes anticancer, 1 inhibitors of topoisomerase II, 2 highlighting their use as valuable candidates in neglected tropical diseases, including leishmaniasis, 3 tuberculosis 4 and tripanosomiasis. 5 Among the naturally occurring naphthoquinones in Tabebuia spp, lapachol, a-lapachone and b-lapachone and xyloidones are the most abundant and studied compounds in these and related species.6 b-Lapachone, in particular, showed a more defined and impressive biological profile in antitumor screenings than the regioisomer a-lapachone or lapachol. 7,8 The molecular mechanism involved in the observed antitumoral and cytotoxic activities of these compounds seems to be mainly related to the ability of the quinone nucleus in participating in redox processes, in which the cascade of one-electron radical enzymaticmediated reactions results in the formation of superoxide radical anions, responsible for cellular damage in living media. 9 In a continuing work concerning the reactivity of lapachol and related quinones, 10,11 we now present our results concerning the reaction of lapachol with primary aliphatic amines. This smooth reaction conduced to new adducts with a cyclic structure consisting of a phenazine nucleus.12 Our initial observation, unlike previous reports, 13 is that lapachol 1 is almost entirely consumed when mixed with primary amines, like n-butylamine, ethanolamine, 3-hydroxypropylamine, 2-methoxyethylamine, 3-methoxypropylamine, and 2-phenylethylamine. The reaction of some few secondary cyclic amines with lapachol have also been described previously, with some unusual spectroscopic data found. 14 Results and DiscussionThe products were formed in reactions at room tempera...
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